1 Technical Field of the Invention
The present invention relates to stators for electric rotating machines that are used in, for example, motor vehicles as electric motors and electric generators, and to methods of manufacturing the stators.
2 Description of the Related Art
Conventionally, there are known stators for electric rotating machines which include a hollow cylindrical stator core and a stator coil. The stator core has a plurality of slots that are formed in the radially inner surface of the stator core and spaced in the circumferential direction of the stator core at a predetermined pitch. The stator coil is comprised of a plurality of electric wires mounted on the stator core. Each of the electric wires includes a plurality of in-slot portions, which are received in the slots of the stator core, and a plurality of turn portions that are located outside of the slots to connect the in-slot portions.
Moreover, there is disclosed, for example in Japanese Unexamined Patent Application Publication No. 2004-104841, a method of interlacing a plurality of electric wires (or coil members) to form a stator coil.
According to the method, one electric wire is progressively interlaced with another electric wire by a half turn at a time by repeating the steps of: rotating the electric wire about its axis by 90° and advancing the electric wire toward the another electric wire by a half turn; and rotating the electric wire further about its axis by 90°.
With the above method, however, a lot of time is needed for interlacing the electric wires. Further, in the case of the electric wires each having a large length, a large-scale apparatus is needed for performing the steps for interlacing the electric wires. Consequently, it is difficult to reduce the manufacturing time and cost of the stator coil. Accordingly, with the above method, it is difficult to mass-produce stators at low cost.